Most Jammie Penguins I encounter usually start the match with a Gordo. I punch it back at them. Some of them shield it, others get smacked in the face by it.
Vacuum Penguin outranges Bowser, but most of his attacks have a slow startup. Fire Breath is always a good approach option. Also, take advantage of the fact that Bowser is more agile than ever, so you can bait an aggressive King Jammies into attacking with his slow attacks and punishing his whiffs.
As with every opponent, Fortress out of shield to punish rolls and blocked attacks.
It's definitely a winnable MU, but it isn't quite that simple. Most competent ones won't open with or spam Gordos for that matter. They'll use it when they can punish you for trying to hit it, when you're trying to land, or other instances where it's safe for them. They can use Gordos to cover the wind-up and cool down of their bigger moves instead of just outright attacking with them.
Also they can throw one that will plow through your Fire Breath and smack you while you sit there. Fire isn't always as safe against D3.
Also their jab is pretty quick and combos into other moves fairly easily, or they can just finish the jab combo for upwards of 18% damage while knocking you pretty damn far away.
I find it better to powershield the Gordos and punish the cool-down for the throw.
Poke with fire occasionally, poke with jab/f-tilt, and take advantage of rolling/dodging more in this MU to better punish their bigger attacks. This isn't one of our hardest MUs but it definitely requires patience and being aware of Gordo trajectories.
